The Coding Humanist

So I ran across an interesting way of marking up Html forms. I thought it was nice, so I decided to bring that into the world of ASP.NET, because there is a (easy to overcome) roadblock in using the method in traditional ASP.NET (it is odd having to distinguish between traditional and MVC...).

A faithful reader of the blog commented on my post the other day about using HttpRuntime vs HttpContext. Anderson's main point is absolutely right, and worth repeating. Here's what he said:

Sometimes I find a discussion on something and I think to myself "you really need to blog this, because you may need to find it again some day and someone else might find it helpful." The adverse side effects of not doing this hit me the other day. I needed this little tidbit, but it took me a while to find it because I didn't blog it the last time I saw it! So here it is.

So I ran into a weird one tonight. I have an ASP.NET page with a grid view and some text boxes. Two of the text boxes have CalendarExtenders on them. On initial load everything is peachy. But I select something in the Grid and fill in the values of the two text boxes on the server side...things go awry. I'm getting a javascript error, "Date.parseLocale is not a function".

In my last post I discussed the virtual path provider in ASP.NET 2.0 the difference between using url rewriting and using the VPP (Virtual Path Provider model) to handle urls for content that doesn't physically exist in the normal folder structure. I've been thinking more about this and my thoughts are crystalizing, so I thought I would flesh them out in a post.

The more I think about it, I think comparing the two things is like comparing apples and oranges. Url rewriting is for taking a url you get and saying "no, I really want you to go here" under the hood. It's about redirection, though it isn't exactly redirection. The VPP system is about creating an extensible ASP.NET page lookup mechanism that keeps you from having to rely on the file system. If my definitions are basically correct, then using url rewriting for handling virtual pages in ASP.NET 2.0 is like using a wrench for a hammer to knock a nail into some wood (which is what I do when I can't find my hammer); it is using a tool for doing something that works but isn't the most ideal for a job. I don't think there was any other way of doing this in 1.1 because the VPP tool was not available, but now that it is (and given what the two techniques actually do), the VPP is the tool we should be using.

Now url rewriting obviously works for this, and is used for this thing on apache as well. And if someone has a system to do this built around url rewriting, it may not be worth rewriting just because ASP.NET 2.0 gives you a shiny new tool. But going forward, this makes sense. If you want to point a request in a different direction, use url rewriting. If you want to show content that doesn't depend on the physical file system structure, use the VPP.

I ran across something very interesting a couple days ago in ASP.NET 2.0 called the VirtualPathProvider. Essentially, it's some ASP.NET infrastructure that abstracts ASP.NET from using the file system directly, and it allows you to "hook in" to it all and serve pages from something other than the file system.

Because the documentation is a little sparse, and because it looked pretty cool, I dug into it, created a sample, and wrote up a short essay about it. The sample can be downloaded from that page.

I think it has some very interesting possibilities. In particular I'm thinking of using it for the blog to do what most blogging platforms do with url rewriting. Currently the pages are viewed on the site through a generic viewer page with a variable in the query string (which is less cool). This would allow me to do something like /2007/3/15/ThisIsMyBlogPostTitle.aspx.

What I would really like to know is what are the advantages and disadvantages of implementing this with either approach. I see how they're both done, and the the virtual path provider way seems like a cleaner approach. Am I missing something? I know for many, like Community Server, that this would not have been an option when the platform was originally written since this is new in 2.0. But I haven't really heard much of a peep on this thing. Is no one else thinking about it? Are you community server folks thinking about it? Anyway, I would love to hear anyone's thoughts. It seems like a cool technology... 

I started reading Programming Microsoft ASP.NET 2.0 Applications: Advanced Topics again recently and ran across something in Dino's book that was piqued my interest. ASP.NET 2.0 comes built with this concept of the Virtual Path Provider.